Method for creating a temporary hypobaric wound space in an intentionally left open surgical wound to diagose substrate losses and prevent exogenous contamination with microorganisms

ABSTRACT

A hypobaric wound space is provided for prophylactic and diagnostic purposes in surgical wounds of the abdomen deliberately left open. The hypobaric wound space provided is established by a combination of an impermeable folio sheet or thin flexible membrane, tissue fluid absorbing gauze or sponge, a drain tube, and a suction device to create hypobaric conditions and prevent wound contamination and infection, and to collect wound fluid to diagnose protein, fluid and other substrate losses on a quantity and quality basis. More specifically the invention provided relates to postoperatively applying negative pressure to the wound space of any surgical wound that was deliberately left open by filling the wound space with medical gauze or any material that is capable of absorbing tissue fluid, sealing the wound space with an impermeable folio or flexible membrane by engaging the folio to the skin of surrounding wound edges, and evacuating air and tissue fluid from the wound space by continuous suction through a drain tube to protect the wound from contamination and infection, and to diagnose fluid and losses substrate losses on a quantity and quality basis

This divisional application is in response to office action filed on 31Oct. 2002 requiring “Election/Restriction” required under 35 U.S.C. 121for claims 9-11 classified in class 606 subclass 216, of applicationSer. No. 09/947,070 filed Sep. 5, 2001 and titled “Prosthesis forabdominal surgery” Class/Subclass 606/215 and “Expressively AbandonedDuring Examination” in favor of Continuation-in-part of application Ser.No. 10/636,728 filed Jul. 7, 2004 with the title “Prosthesis and methodfor lowering abdominal pressure” Class/Subclass 606/213, currently“docketed for examination”. Priority is claimed based on provisionalpatent application No. 0/230,202 filed Sep. 5, 2000.

The present invention relates to contamination and infection prophylaxisof surgical wounds of the abdomen that were deliberately left open andremoving wound fluid continuously for diagnostic purpose by creating ahypobaric space with a combination of three elements of biocompatiblematerial termed hypobaric wound shield (HBS) or Hypopack. The Hypopackconsists of three elements of biocompatible material:

-   (1) (Element one) An impermeable folio or plastic drape or other    impermeable fabric or flexible membrane having a side that is or may    be rendered adhesive covering the entire wound and engaging onto the    surrounding skin for sealing the wound space off the environment.-   (2) (Element two) Surgical gauze or sponge or sponge-like material    that is capable of absorbing wound fluid.-   (3) (Element three) wide lumen drainage tube of sufficient wall    rigidity to prevent collapse under negative pressure produced by an    attached suction pump with manometer.

More particularly, this invention relates to applying continuousnegative pressure to an open surgical abdominal wound by sealing thewound with an impermeable folio with adhesive properties on one side andengaging the folio to the skin of surrounding wound edges and evacuatingair from the wound space by continuous suction to protect the wound fromcontamination and uncontrolled fluid losses. Definition List 1 TermDefinition Hypobar A pressure below normal atmospheric pressure.Hypobaric wound A combination of three elements of shield (HBS)biocompatible material that produces and maintains a negative pressurein an open surgical wound, which prevents contamination of the wound andthat allows for measuring of body fluid losses. Hypopack Short name forHBS. Open wound Any surgical wound that could not be closed and/or wasdeliberately left open with or without the fascia separated. Element onean impermeable folio or plastic drape or other impermeable fabric havinga side that is or may be rendered adhesive to cover the entire wound andto engage onto the surrounding skin for sealing the wound space from theenvironment, Adhesive Any substance that is used to bond two surfacestogether. Element two Any surgical gauze or sponge or sponge-likematerial that is capable of absorbing wound fluid and that may or maynot have antimicrobial and/or antiviral or wound healing enhancingproperties. Element three Any drainage tube with a lumen sufficientlylarge to transport body fluids, that is made of any biocompatiblematerial and that has sufficient wall rigidity to prevent collapse undernegative pressure up to −200 mm Hg. Lumen The hollow part of a tube.Abdominal Increase of intra abdominal pressure hypertension above normalphysiological levels. Compliance The potential of a structure such asthe fascia to expand. Organ system The various organ structures of thebody that function in concord. Infusion bag A bag made of biocompatibleplastic material attached to a small tube that is used to add externalfluids and nutrition into the vascular system. Fistula An opencommunication between a physiological or pathological hollow structureof the body with another such structure or the skin. Visceral edemaSwelling of the visceral or intra- abdominal organs. Omentum Anapron-like structure of loose connective tissue and immunologicallycompetent cells that normally lays on top of the intestines beneath theabdominal wall. Epigastrium Small area on the anterior abdominal walland inferior to the costal margins of the anterior chest wall. Rectusmuscle Longitudinal segmented muscle lateral to the abdominal midlinethat is enfolded in the abdominal fascia. Axillae Plural of axilla.Fascial expander Any mesh or fabric that is used to bridge prosthesisthe fascia gap in case of fascial dehiscence. Manometer A device tomeasure pressure. Laparotomy Surgical opening of the abdominal cavity.Surgical wound Wound that is created by a surgical incision as opposedto traumatic wound that is created by non surgical trauma. Vacuum Aspace absolutely devoid of matter. Substrate The base on which anorganism lives

A number of prior art references emphasize the value of hypobaric wounddressings or the provision of hypobaric pressure in the space above thesurface of chronic wounds. Often the term vacuum is inaccurately used inprior art, because it is not possible to create a true vacuum in awound. A true vacuum would be incompatible with cell survival becausethe fragile cellular wall structure would burst from the pressuredifference between intracellular pressure and a vacuum with virtually nopressure at all. The following recent U.S. patents deal with the natureof devices that can create hypobaric conditions for enhancing woundtreatment: U.S. Pat. Nos. 6,855,135, 6,725,794, 6,071,304, 5,645,081,5,636,643, 4,969,880, 4,655,754, 4,569,674, 4,382,441, and 4,112,947.All of such references are incorporated herein by reference for purposesof disclosing the nature of such hypobaric treatment of wounds which isdifferent from the present invention where the hypobaric conditionscreated are not meant to enhance healing of the wound directly. Thepaper of Valenta, A. in “American Journal of Nursing. April 1994. “Usingthe Vacuum Dressing Alternative for Difficult Wounds” provides aninsight into the claims of prior art to improve wound healing. TheHypopack is not used for treatment to enhance wound healing. Instead,the Hypopack is used for prophylaxis of contamination and infection anddiagnosis of fluid and substrate losses on a quantity and quality basisfrom the abdominal cavity by temporarily covering a wound that waspurposefully left open by the surgeon until said wound can be closedpermanently, usually after three to eight days.

U.S. Pat. Nos. 6,855,135 and 6,725,794 were filed on May 13, 2002 andNov. 27, 2001 respectively. Said two most recent patents discuss indetail all prior art that claims beneficiary healing effect of providinga “vacuum” in the space above the wound to promote healing in chronicwounds. The present invention deals with acute wounds exclusively anddoes not claim to promote wound healing.

U.S. Pat. Nos. 5,645,081 and 5,636,643 disclose a method of treatingtissue damage by applying negative pressure to a wound sufficientduration and magnitude to promote tissue migration and thus facilitateclosure of the wound. FIG. 1 of U.S. Pat. No. 5,645,081 discloses anopen cell polyester foam section covering the wound, a flexible hollowtube inserted into the foam section at one end and attached to a vacuumpump at another end, an adhesive sheet overlying the foam section andtubing to adhere to the skin surrounding the wound in order to form aseal that allows the creation of a “vacuum” when the suction pump isoperating. The present invention is different because it does no claimto promote tissue migration and wound healing. In other prior artsimilar systems are describe for the purpose of irrigating a wound (U.S.Pat. Nos. 4,382,441 and 4,112,947). The present invention is not used toirrigate the wound.

The present invention is intended to be used in circumstances that forcea surgeon to leave open an abdominal wound. Said wounds are primarilysterile and subject to contamination with exogenous microorganisms. Saidwounds are also subject to uncontrolled fluid losses, and losses ofessential vital substrates. Contamination of open wounds may lead tolife threatening infection. Uncontrolled fluid losses may deplete thepatient's proteins. Physiological protein balance is essential for woundhealing. If this balance is upset due to uncontrolled losses, thesubstitution of proteins becomes an important factor in wound healingand survival.

Circumstances that force a surgeon to leave a wound open may come about,for example, in abdominal compartment syndrome that occurs whenintra-abdominal pressure rises acutely, because the abdominal cavitywith its content is contained within an envelope of limited compliance.Increasing intra-abdominal volume, as seen with inflammatory edema,translates directly into pressure increases and, beyond a certainthreshold, strangulates blood flow to all structures within theenvelope.

Abdominal compartment syndrome impairs functions of vital organ systemsin humans and animals. With sustained abdominal hypertension above acritical value, high mortality rates are observed.

When blood flow is diminished cells do not receive sufficient substratesand oxygen that is essential for generating energy to sustain life.Cellular death may lead to sequential organ system dysfunction and, ifnot treated, to death.

The first publication about renal function impairment in the presence ofabdominal hypertension was published in 1876, by E C Wendt (Arch.Heilkunde. 1876; 17:527). Clinicians, however, did not appreciate thecondition for a century and only recently began treating abdominalhypertension by leaving the abdomen open with the fascias separated ortemporarily covering the fascial defect over exposed organs with anyfabric including infusion bags and meshes as described in U.S. Pat. No.4,452,245 (Schein, et al, J Am College of Surgeons 180:745-753, 1995).Sugerman developed an external device to treat increased intra-abdominalpressure (U.S. Pat. No. 5,893,368).

Leaving the abdomen open, however, is associated with high mortalityrates, fistula formation, and large incisional hernias. All wounds leftopen become infected. The use of available meshes (U.S. Pat. No.4,452,245) to bridge the gap between fascias is associated withsimilarly high infection and mortality rates.

With all methods the open wound is exposed and subject to exogenousinfection that may foster said detrimental events leading to organsystem dysfunction and death. In a recent publication the open abdomentechnique is advocated as the treatment of choice for abdominalcompartment syndrome. (Miller, P R, J. Trauma 53:843-849, November 2002)The authors observed high intra-abdominal pressure and abdominalcompartment syndrome from visceral edema in 122 of 646 patients whounderwent laparotomy for trauma, and the abdomen of these 122 patientswas left open after incising the fascia. More than 40% died, by andlarge of infection.

There is obviously a need for a method that temporarily covers the woundand prevents exogenous contamination of any surgical wound that cannotbe closed at the end of a surgical intervention. Exogenous contaminationmay be prevented by protecting the open wound with an impermeable foliocover sealed to the adjacent skin and creating hypobaric conditionswithin the wound space by applying negative pressure through a tube thatnot only evacuates air from the wound space but also any wound fluidlosses, which provides diagnostic information that will help todetermine how much fluid, protein and other substrate must be replacedor substituted.

DESCRIPTION OF DRAWINGS

FIG. 1 shows the anterior abdominal cavity and anterior abdominal andchest wall with an open abdominal wound and dehiscent fascia that iscovered with the present invention, the Hypopack depicting its threeelements in place in an open wound to show the relation of element one,the impermeable folio or flexible membrane 11, element two the fluidabsorbing material 12, and element three the drain tube 13.

FIG. 2 is a cross section of a wound that is covered by a hypobaricwound shield and where the space between the fascial borders has beenbridged with a synthetic mesh.

Numbers in the FIGS. 1 and 2 have the following meaning:

-   (1) Abdominal Cavity (1)-   (2) Intestines (2)-   (3) Omentum (3)-   (4) Fascia left side (4)-   (5) Abdominal rectus muscle and surrounding fascia, right side (5)-   (6) Subcutaneous tissue (6)-   (7) Skin (7)-   (8) Epigastrium (8) (not shown on FIG. 2)-   (9) Chest wall (9) (not shown on FIG. 2)-   (10) Axillae (10) (not shown on FIG. 2)-   (11) Impermeable drape or folio (element one of the Invention) (11)-   (12) Gauze or body fluid absorbing material/sponges (element two of    the invention) (12)-   (13) Drain tube (element three of the invention) (13)-   (14) Lumen of drain tube (14)-   (15) Mesentery of folio to seal drain conduit (15) (not shown on    FIG. 2)-   (16) Suction device e.g. a suction pump with manometer (16)-   (17) Mesh or fascial expander prosthesis (17) (not shown on FIG. 1)

DESCRIPTION OF PREFERRED EMBODIMENT

The preferred embodiment of the invention includes the three elements ofthe invention in a sealed outer package with a sterile interior such asa transparent plastic bag for storage until use.

The preferred method of using the device or implant of the presentinvention is shown with the help of illustrations FIGS. 1 and 2. When asurgeon desires to protect an operative incision that was intentionallyleft open from becoming contaminated the hypobaric would shield may beformed by doing the following:

Any surgical wound that was left open in general or any open abdomen inparticular as shown in FIGS. 1 and 2 may be covered by using thehypobaric wound shield. This is accomplished by packing element one(gauze or any body fluid absorbing sponge/material) 12 into the woundspace between the fascias 3 and subcutaneous tissue 4 up to the level ofthe skin 5. A suction drain tube (element three) 13 and 14 is imbeddedinto element one 12. An impermeable folio, such as a plastic drape(element two) 11 having an adhesive side is engaged onto the skin tocover the entire wound and surrounding skin, and creating an airtighttunnel 15 for the drain tube. This seals the abdominal cavity and keepsit sterile. The area of the skin that is covered by the impermeablefolio, such as a plastic drape 11, should cover a distance sufficientlylarge to prevent communication (leaks) between skin and folio andthereby preventing communication (leaks) between wound and environment.Air and wound fluid are immediately removed from the wound space byconnecting the lumen 14 of the drain tube 13 to a suction device (pump)that is capable of producing hypobaric conditions with negative pressureup to −100 mm Hg. Additionally, the suction device may be connected to acontainer to collect wound fluid for measurement of protein losses andother factors for possible replacement.

The hypobaric wound shield must be replaced when negative pressurecannot be maintained any longer. This may happen accidentally orintentionally during wound inspection.

All materials used must be biocompatible and sterile before use Allcomponents of the hypobaric wound shield are packaged in an internallysterile package such as a transparent plastic bag for storage until use.

REFERENCES CITED

Besides the U.S. patents cited relevant references are cited below.

-   1. Dunlop et al., Br. J. Surg., 77: 562-563, 1990, “Vacuum drainage    of groin wounds after vascular surgery: a controlled trial”.-   2. Fleischmann, W. Wund Forum Spezial. IHW '94. “Vakuumversiegelung    zur Behandlung von Problemwunden” (with English translation: Vacuum    Sealing for Treatment of Problematical Wounds.-   3. Saunders, J. W., The Lancet, pp. 1286-1287, Jun. 28, 1952,    “Negative-Pressure Device for Controlled Hypotension During Surgical    Operations”-   4. Schein, M. et al., Journal Am College of Surgeons 180:745-753,    1995, “The abdominal compartment syndrome: the physiological and    clinical consequences of elevated intra-abdominal pressure.-   5. Valenta, A., American Journal of Nursing. April 1994. “Using the    Vacuum Dressing Alternative for Difficult Wounds.”-   6. Wendt, E. C., Archiv Heilkunde, Vol. 17, p. 527-527, 1876. “Über    den Einfluss des intraabdominellen Druckes auf die    Absonderungsgeschwindigkeit des Harnes.”

1. The method of temporarily hermetically sealing an open surgical woundof the abdomen for diagnostic and prophylactic purposes with a hypobaricwound shield to keep the wound sterile by preventing exogenouscontamination and infection and to allow for collection of wound fluidsfor diagnosis of fluid and substrate losses on a quantity and qualitybasis. The hypobaric wound shield consists of three element ofbiocompatible material: a. (Element one) an impermeable flexible folioor flexible membrane or plastic drape or other impermeable fabric havinga side that is or may be rendered adhesive to cover the entire wound andto engage onto the surrounding skin for sealing the wound space off fromthe environment, b. (Element two) surgical gauze or sponge orsponge-like material that is capable of absorbing wound fluid, and c.(Element three) a wide lumen drainage tube of sufficient wall rigidityto prevent collapse under negative pressure used. The method furtherincludes placing element two into the open surgical wound between thedehiscent skin, fascia and subcutaneous tissue onto the wound ground,imbedding a drain tube (element three) within or adjacent to elementtwo, guiding the drain tube from the wound space through the folio byforming a “mesentery” or by other means that keeps the wound spacesairtight, and connecting the drain tube to a suction device or pump toproduce negative pressure within the wound space. Element one is used tocover the wound with elements two and three including the adjacent skinto which it engages in an airtight bond.
 2. To keep the system of claim1 under continuous negative pressure of a magnitude that is tolerated bytissue without damage, and collect wound fluid by maintaining the draintube attached to the suction device and attached collection container inorder to prevent the portion of the folio sheet that is engaged to theadjacent skin from detaching thereby preventing air and fluid leaks. 3.To place the three biocompatible elements of the hypobaric wound shieldwithin a clean packaging for sterilization and ensuring sterile storageuntil use.